Through a process known as “budget reconciliation,” the House and Senate can fast-track debt limit, budget and tax bills through both chambers with simple majority votes. The rub is that in order to use the reconciliation process, you must first pass a budget blueprint teeing up a debt limit hike.

Congress hasn’t accomplished a joint budget resolution — technically required by law — since 2009, when Nancy Pelosi still held the speaker’s gavel. The budget agreement signed into law in December doesn’t qualify; that law did not provide for a debt limit increase or fast-track rules to pass one, even though under its terms deficits would still continue as far as the Congressional Budget Office’s eyes can see.

Jumping through the hoops required by an old-school budget resolution would have chewed up more time heading into Christmas. And it would have required the messy process of sending the larger legislation through the relevant committees. Instead, this was a deal negotiated by two people: House Budget Chairman Paul Ryan, R-Wis., and Senate Budget Chairwoman Patty Murray, D-Wash., who usurped the authority of other committees. Congress went along, with lawmakers eager to get home for the holidays.

"What this issue is all about is very simple. Will we allow the debt ceiling to be raised by an unlimited amount with just a 50-vote threshold?" Cruz said in May.

That makes last week's nailbiter vote nearly a year in the making.

Technically, the debt ceiling was suspended for a year (equivalent to raising it an "unlimited amount") with a simple majority. On final passage, every Senate Republican voted no. But to get there, Senate Minority Leader Mitch McConnell, R-Ky., and his leadership team faced the crucible test of voting to end debate . McConnell later defended his vote, taking credit for avoiding a historic default on the debt. The power of reconciliation rules was most apparent in 2010, when Democrats, faced with Scott Brown’s stunning victory in the Massachusetts special Senate election to replace the late Sen. Ted Kennedy, used them to pass a sidecar to the Senate’s version of the Affordable Care Act in order to secure the passage of the health law in the House.

Republicans understand the power of reconciliation themselves, having used it repeatedly to pass tax cuts and other budget measures over the objections of Democrats when they controlled both chambers and the White House. Sen. Roy Blunt, R-Mo., anticipating a potential Republican takeover in the 2012 election, called the budget — and thus the ability to use reconciliation — the “key to the kingdom” for the GOP .